731988721 has 2 divisors, whose sum is σ = 731988722. Its totient is φ = 731988720.

The previous prime is 731988667. The next prime is 731988727. The reversal of 731988721 is 127889137.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 639078400 + 92910321 = 25280^2 + 9639^2 .

It is an emirp because it is prime and its reverse (127889137) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 731988721 - 2¹⁵ = 731955953 is a prime.

It is not a weakly prime, because it can be changed into another prime (731988727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 365994360 + 365994361.

It is an arithmetic number, because the mean of its divisors is an integer number (365994361).

Almost surely, 2^731988721 is an apocalyptic number.

It is an amenable number.

731988721 is a deficient number, since it is larger than the sum of its proper divisors (1).

731988721 is an equidigital number, since it uses as much as digits as its factorization.

731988721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 46.

The square root of 731988721 is about 27055.2900742165. The cubic root of 731988721 is about 901.2282493566.

The spelling of 731988721 in words is "seven hundred thirty-one million, nine hundred eighty-eight thousand, seven hundred twenty-one".